The present invention relates to an automatic control system for controlling the motions of at least a power member controlled by a servo device. The present invention more particularly relates to a control system for controlling a plurality of hydraulic power units to be simultaneously actuated to perform a cycle of motions.
Remote control devices to actuate a power member, for example a hydraulic cylinder are used principally to control the working direction, the speed and the power of the cylinder, and the remote control device is connected via an electrical control circuit to a proportional solenoid valve. In response to a manual adjusting position of the remote control device the control circuit generates a current for the solenoid of the valve such that the power cylinder is actuated by the solenoid valve. To automatically control a predetermined cycle of motion of the cylinder the artisan is aware of prior art learning systems according to which signals corresponding to successive positions of the cylinder are read-out from a memory. For loading the memory the positions corresponding to desired motions of the cylinder governed by a point setter or transmitter are measured and stored in the memory.
In programming a desired pattern or cycle of motions problems primarily arise when the motions of a number of drive units must be coordinated to each other which means that the control is performed simultaneously in a number of axes. This is the case, for example, when multi-armed robots are automatically controlled, or, when excavators have to perform a predetermined pattern of excavating motions. The control of all the single valves controlling the power units is performed by a multiple axis potentiometer called joy-stick. Since a number of valves must be controlled by pivoting the joy-stick of the transmitter in a number of directions, the operating person encounters problems to find the desired cycle of motions free of error to be read-in the memory while actuating the joy-stick.
The aim of the present invention is to load the data determining a cycle of motions of at least a power unit in a memory such that each desired successive motion is simply and safely loaded in the memory while making possible corrections of any errors. In particular the aim of the present invention is to ensure that the reading-in and reading-out of data may be stopped to perform corrections or, respectively to modify the cycle of motions via a transmitter.